Technical Field
The present disclosure relates to a probe head, and more particularly, to a probe head of a vertical probe card.
Description of Related Art
While testing a semiconductor chip, tester uses a probe card to electrically connect a DUT (Device Under Test) and obtain testing results of the DUT through signal transmission and signal analysis. A conventional probe card is usually constituted by a circuit board and a probe head, or further includes a space transformer disposed between the circuit board and the probe head. The probe head is equipped with a plurality of probes arranged to correspond to electrical contacts of the DUTs, so as to contact the electrical contacts with the probes at the same time.
FIG. 10 is an exploded view of a conventional probe assembly 71. The probe assembly 71 includes a probe 710 and a spring sleeve 711 sleeved at the exterior of the probe 710. FIG. 11 is a partial cross-sectional view of a probe card adopted in the probe assembly 71. For convenience of explanation, the geometric proportions of components in FIG. 11 are not corresponded with those in FIG. 10. The probe card includes a probe head 7 and a circuit substrate 8. The probe head 7 includes a probe base 70 and a plurality of probe assemblies 71 (FIG. 11 only shows one of the probe assemblies 71). The circuit substrate 8 can be a circuit board used to electrically connect a tester (not shown). Alternatively, the circuit substrate 8 can be a space transformer and is disposed between a circuit board (not shown) used to electrically connect a tester (not shown) and the probe head 7.
The approach for bonding the probe 710 and the spring sleeve 711 of the probe assembly 71 is pressing a bonding section 711a at the lower end of the spring sleeve 711 to the probe 710 and then fixing the bonding section 711a and the probe 710 by welding (e.g., spot welding). The probe base 70 is constituted by an upper guiding board 700, a middle guiding board 701, and a lower guiding board 702 (or the middle guiding board 701 can be omitted). The guiding boards form a plurality of installation holes 703 (FIG. 11 only shows one of the installation holes 703). Each of the installation holes 703 is constituted by an upper guiding hole 700a of the upper guiding board 700, a middle guiding hole 701 of the middle guiding board 701, and a lower guiding hole 702a of the lower guiding board 702, and is used to install one of the probe assemblies 71. The bonding section 711a of the spring sleeve 711 turns towards the upper guiding board 700 and sequentially passes through the upper guiding hole 700a of the upper guiding board 700 and the middle guiding hole 701a of the middle guiding board 701, so as to be installed in the lower guiding hole 702a of the lower guiding board 702. The lower end of the probe 710 passes through a through hole 702b of the lower guiding board 702, so that the meanwhile, the bottom surface of the bonding section 711a of the spring sleeve 711 is supported on the bottom surface of the lower guiding hole 702a of the lower guiding board 702. Therefore, the probe assembly 71 can be maintained in the upper guiding board 700, the middle guiding board 701, and the lower guiding board 702 without falling.
However, while assembling or repairing the above-mentioned probe head 7, following problems often occur. Problem (1): if the probe head 7 is turned over (i.e., the upper guiding board 700 is located under the lower guiding board 702), all of the probe assemblies 71 will fall out of the probe base 70. Hence, the circuit substrate 8 must be tilted or placed upside down (i.e., make the surface of the circuit substrate 8 used to contact the probe head 7 face downwards) while assembling or repairing, which may increase assembling time or repairing time. Problem (2): while disassembling the probe head 7 the tails of the assemblies 71 are adhered to the electrical contacts on the circuit substrate 8 and fall out of the probe base 70. Problem (3): the guiding holes 700a, 701a, and 702a of the guiding boards 700, 701 and 702 are manufactured before the assembling of the guiding boards 700, 701, and 702, so assembly errors or machining errors may occur to the guiding holes 700a, 701a, and 702a, which makes the inner wall of the installation hole 703 uneven. Hence, the probe assembly 71 may got stuck while being placed into the installation hole 703 and needs to be pressed or patted at the tail by using tweezers. However, during the pressing or patting, the probe assembly 71 may popped out of the installation hole 703 (due to the elastic force generated by the spring sleeve 711) when the tweezers leave the tail of the probe assembly 71. Problem (4): While cleaning the tail of the probe assembly 71, the probe assembly 71 may also popped out of the installation hole 703 when a brush presses the tail of the probe assembly 71. Problem (5): the position of the junction 704 of the upper guiding board 700 and the middle guiding board 701 is corresponded with one of spring sections 711b of the spring sleeve 711, and the position of the junction 705 of the middle guiding board 701 and, the lower guiding board 702 is corresponded with another of the spring sections 711b of the spring sleeve 711. If the junctions 704 and 705 are not flushed with each other due to the assembly errors of the guiding boards 700, 701 and 702 and thus makes the inner wall of the installation hole 703 be uneven, the spring sections 711b may easily got stuck at the uneven junctions 704 and 705. As a result, the probe assembly 71 needs to be repaired, which is difficult and time consuming.